Demographic, clinical, dietary, and laboratory characteristics of adults enrolled in the NHANES III, based on the presence and stage of CKDa
| Characteristic | Non-CKD | CKD | P | |||
|---|---|---|---|---|---|---|
| Stage 1 | Stage 2 | Stage 3 | Stage 4 or 5 | |||
| Prevalence (%) | 86.2 | 6.2 | 3.5 | 3.8 | 0.2 | |
| Age (yr) | 41.1 ± 0.4 | 43.7 ± 0.8 | 59.5 ± 0.9 | 70.2 ± 0.8 | 70.7 ± 1.8 | <0.0001 |
| Male gender (%) | 48.4 | 44.6 | 53.0 | 38.7 | 39.6 | 0.0070 |
| Race/ethnicity (%) | ||||||
| white | 76.0 | 64.8 | 80.9 | 86.8 | 66.7 | |
| black | 10.6 | 17.5 | 10.7 | 7.5 | 23.1 | <0.0001 |
| Mexican American | 5.5 | 7.3 | 3.0 | 1.4 | 2.8 | |
| other | 7.9 | 10.4 | 5.4 | 4.3 | 7.4 | |
| Serum creatinine (mg/dl) | 1.0 ± 0.0 | 1.0 ± 0.0 | 1.2 ± 0.0 | 1.5 ± 0.0 | 4.0 ± 0.4 | <0.0001 |
| eGFR (ml/min per 1.73 m2) | 103.7 ± 0.6 | 115.2 ± 1.0 | 76.8 ± 0.4 | 50.8 ± 0.3 | 21.1 ± 1.3 | <0.0001 |
| Vitamin D levels (ng/ml; %) | ||||||
| >30 | 45.9 | 33.4 | 39.5 | 36.5 | 17.0 | |
| 15 to 30 | 45.7 | 52.5 | 51.4 | 52.8 | 55.8 | <0.0001 |
| <15 | 8.4 | 14.1 | 9.1 | 10.7 | 27.2 | |
| Taking vitamin D supplements (%) | 27.9 | 23.2 | 25.6 | 27.1 | 17.1 | 0.0800 |
| Total vitamin D intake (diet + supplements; IU/d) | 309.1 ± 7.3 | 282.0 ± 13.4 | 324.5 ± 22.3 | 319.6 ± 19.2 | 288.7 ± 57.9 | 0.3000 |
| Current smokers (%) | 29.2 | 32.6 | 23.2 | 13.7 | 19.6 | <0.0001 |
| Hypertension (%) | 17.6 | 33.3 | 59.3 | 72.7 | 74.4 | <0.0001 |
| BMI (kg/m2) | 26.3 ± 0.1 | 27.2 ± 0.3 | 28.2 ± 0.5 | 27.7 ± 0.2 | 26.7 ± 1.1 | <0.0001 |
| Diabetes (%) | 4.6 | 18.6 | 28.3 | 21.7 | 29.8 | <0.0001 |
| Non-HDL cholesterol ≥160 (mg/dl, % | 38.7 | 42.9 | 57.4 | 68.4 | 50.2 | <0.0001 |
| Serum CRP (mg/dl; %) | ||||||
| undetectable | 74.1 | 60.6 | 58.7 | 50.8 | 35.1 | |
| 0.30 to 0.99 | 19.8 | 24.1 | 27.0 | 30.8 | 37.4 | <0.0001 |
| ≥1 | 6.1 | 15.2 | 14.3 | 18.4 | 27.4 | |
| Serum albumin (g/dl) | 4.2 ± 0.0 | 4.2 ± 0.0 | 4.1 ± 0.0 | 4.0 ± 0.0 | 3.8 ± 0.1 | <0.0001 |
| Corrected serum calcium (mg/dl) | 9.2 ± 0.0 | 9.3 ± 0.0 | 9.4 ± 0.1 | 9.5 ± 0.0 | 9.4 ± 0.1 | <0.0001 |
| Serum phosphorus (mg/dl) | 3.5 ± 0.0 | 3.4 ± 0.0 | 3.4 ± 0.0 | 3.5 ± 0.0 | 4.1 ± 0.1 | <0.0001 |
| No medical insurance (%) | 13.6 | 14.7 | 7.6 | 2.5 | 0.1 | <0.0001 |
| Education <12 yr (%) | 19.7 | 27.9 | 32.8 | 43.8 | 49.4 | <0.0001 |
| Income <200% of federal poverty level (%) | 32.6 | 42.0 | 36.8 | 45.9 | 55.1 | <0.0001 |
↵a BMI, body mass index; CKD, chronic kidney disease; CRP, C-reactive protein; eGFR, estimated GFR; NHANES III, Third National Health and Nutrition Examination Survey.